KR20030018337A - Fuel injection system for diesel engine - Google Patents

Abstract

PURPOSE: A fuel injector for a diesel engine is provided to reduce NOx and fine particles and to improve a fuel consumption ratio of a vehicle by reducing an injection delay time and a rapid spill. CONSTITUTION: A fuel injector includes an injection pipe(7a) for supplying fuel from an injection pump and an injection nozzle(5) for injecting fuel into a combustion chamber when the pressure of fuel exceeds a reference value. A flow-limit(10) is installed between an end of an injection pipe(7a) and an inlet pipe(5b) of the injection nozzle(5) to limit a fuel flow. The flow-limit(10) is opened when pressure of fuel exceeds a predetermined level so that fuel flows towards the injection nozzle(5). The flow-limit(10) is closed when pressure of fuel is under the predetermined level, so that high pressure is maintained in the injection nozzle(5).

Description

Fuel injection system for diesel engine {Fuel injection system for diesel engine}

The present invention relates to a device for injecting fuel of a diesel engine, and in particular, by restricting the fuel flow flowing into the injection nozzle for injecting the fuel, to maintain the residual pressure in the injection nozzle pipe at high pressure to prevent the injection delay and post-injection under certain conditions And a fuel injection device for a diesel engine.

In general, a fuel supply device for an automobile is a device for supplying a suitable mixer required by an engine, and a fuel pump, a fuel pump for removing impurities in a fuel, a fuel pump for delivering fuel to a carburetor, or a fuel injector, and an engine for making an engine. And a vaporizer or a fuel injection device for supplying to the fuel cell, and a fuel pipe for connecting such devices.

On the other hand, a diesel engine is similar to a gasoline engine in kinematics, but in the combustion process of a fuel, a gasoline engine compresses a mixture of air and fuel and then ignites it with an electric flame, whereas a diesel engine sucks only air and uses a high compression ratio. Compressed air is heated to a high temperature of 500 ° C. or higher, and then sprayed into a mist of fuel in the injection nozzle to self-ignite. The diesel engine has a large difference in fuel system from a gasoline engine.

In other words, the diesel engine requires an injection device for injecting fuel into the combustion chamber at an appropriate pressure and time instead of an electric ignition device. The injection device includes an injection pump and an injection nozzle for supplying fuel from the injection pump.

1 shows a configuration of a fuel supply device of a diesel engine. The fuel supply device includes a fuel tank 1 for storing fuel, a supply pump 2 for transporting fuel from the fuel tank 1, and the supply thereof. A fuel filter 3 for removing impurities from fuel pumped from the pump 2 to the injection pump 4, and a fuel supplied through the fuel filter 3 temporarily stored in a fuel chamber (not shown), and then Injection pump (4) for supplying the injection nozzle (5) through the injection pipe (7a) under a pressure of 5, and the injection nozzle (5) for receiving the high-pressure fuel supplied from the injection pump (4) .

In the conventional diesel engine, the injection nozzle 5 is a needle 5a of the injection nozzle 5 when the fuel pressure in the injection nozzle 5 rises above the opening pressure by the high pressure fuel feeding of the injection pump 4; 2) is lifted up, fuel is injected into the combustion chamber, and the pressure drop occurs during the downstroke according to the cam diagram of the injection pump 4, the needle is closed by the closing pressure of the nozzle, and the injection is completed. Will be made.

During the injection operation as described above, the injection nozzle 5 is closed by the closed transformer pressure, and the reflected wave generated by the pressure inertia has a frequency and goes to the injection pump so that the fuel flows back to the pump for pressure stability.

At this time, the pipe 7a between the injection pump 4 and the injection nozzle 5 has a certain degree by a constant pressure valve (CPV) (not shown) on the injection pump 4 side. The pressure is maintained so that the injection timing is slightly faster due to the injection pressure and the residual pressure in the pipe during the next cycle injection.

However, such a conventional fuel injection nozzle has a problem that only one fuel injection can be performed in one cycle, and the injection pressure is characteristic of the fuel pump, that is, the cam lift and cam profile, the holding pressure of the positive pressure valve, and the fuel injection nozzle. It is determined only by the fuel injection timing according to the injection rate.

In order to solve the above problems, the present invention provides a means for restricting the flow of fuel between a fuel injection nozzle and a connection portion of a pipe for supplying fuel to the injection nozzle, thereby increasing the pressure in the injection nozzle tube to a high pressure. Diesel engine that can improve fuel efficiency by maintaining nitrogen oxide (NOx) and fine material (PM) by maintaining post injection at specific pressure and reducing rapid spill effect and injection delay period. The purpose is to provide a fuel injection for the fuel.

1 is a view showing the configuration of a fuel supply device of a general diesel engine,

2 is a cross-sectional view showing a state in which the flow limit of the present invention is installed at the inlet side of the injection nozzle.

3 is a cross-sectional view showing the pressure in the tube and the post-spraying state of the injection nozzle when the flow limit of FIG. 2 is closed;

4 is an exploded perspective view showing the flow limit configuration of the fuel injection device of the present invention;

5 is a cross-sectional view of the closed state of the flow limit of FIG.

6 is a cross-sectional view of the open state of the flow limit of FIG.

7 is a flowchart showing the operation procedure of the fuel injection device equipped with the flow limit of the present invention.

Explanation of Reference Symbols in Major Parts of Drawings

5-Nozzle 5a-Needle

5b-Inlet pipe 7a-Injection pipe

10-Flow Limit 101-Housing

102-Ball 103-Retainer

104-Seat Valve 105-Compression Spring

106-Shim

In order to achieve the above object, the present invention comprises an injection pump, and an injection nozzle connected to the injection pump and the injection pipe via the injection nozzle for injecting fuel supplied from the injection pump under a predetermined pressure to the combustion chamber. In addition, the connection part of the injection pipe and the injection nozzle provides a fuel injection device for a diesel engine, characterized in that the flow restriction means for limiting the flow of fuel flowing to the injection nozzle is installed.

Here, the flow restricting means is a hollow housing having one end coupled in communication with the end of the injection pipe and the other end coupled in communication with the inlet end of the injection nozzle, a ball closing the inlet end of the hollow portion of the housing, and A retainer inserted and fixed to the outlet end side of the hollow portion, an elastic member elastically supporting the ball between the ball and the retainer, and a ball and elastic member front end portion so that the elastic member can support the ball A seat valve seated and supported, and a shim interposed between the rear end of the elastic member and the retainer to adjust the elastic force of the elastic member.

Hereinafter, a preferred embodiment of a fuel injection device for a diesel engine according to the present invention will be described in detail with reference to the accompanying drawings.

2 and 3 show the configuration of the fuel injection device according to the present invention, the fuel injection value is largely injection pipe 7a for supplying fuel from the injection pump 1 (see Fig. 1), and this injection pipe ( It is provided between the injection nozzle 5 which injects the fuel supplied to the combustion chamber when the fuel conveyed from 7a) is more than opening pressure, and between the end of the injection pipe 7a and the inlet pipe 5b of the injection nozzle 5a. And limit the flow of fuel therebetween.

Specifically, the flow limit 10 is a fuel pressure pumped through the injection pipe (7a) is opened above the set pressure to allow the flow of fuel to the injection nozzle (5) and closed below the set pressure to the injection nozzle ( The fuel flow from 5) to the injection pump 1 (see FIG. 1) is interrupted, so that once the fuel injection is made in the injection nozzle 5, the residual pressure in the injection nozzle 5 is maintained at a high pressure and the after injection is performed. To induce.

4 to 6 is a view showing the structure of the flow limit 10 as described above, the flow limit 10 is coupled to the front end portion in communication with the end of the injection pipe (7a) and the rear end of the injection nozzle (5) A hollow housing 101 coupled to the inlet pipe 5b, wherein the hollow portion of the housing 101 is between the front portion 101a and the middle portion 101b, and the middle portion 101b and the rear portion ( Steps are respectively formed between 101c).

In addition, a retainer 103 fixedly supported by an end of the injection nozzle 5 inlet pipe 5b is inserted into the rear portion of the hollow portion of the housing 101, and the front portion 101a is inserted into the housing middle portion 101b. Ball 102, which is supported by a step with the step of opening and closing the front portion (101a), seat valve 104 (seat valve) is seated and supported from the ball 102, the seat valve 104 ) And a compression spring 105 interposed between the retainer 103 and the retainer 103 to elastically support the ball 102 and the seat valve 104, and to adjust the elastic force of the compression spring 105. It consists of a shim interposed between the rear end and the retainer 103.

Here, the elastic force of the compression spring 105 may be adjusted by adjusting its elastic modulus and thickness of the shim 106, the seat valve 104 is formed with a plurality of grooves 104a on the outer peripheral surface The fuel is supposed to flow through him.

The flow limit 10 as described above has a ball 102 as shown in FIG. 5 when the fuel pressure pumped through the injection pipe 7a is smaller than the elastic force of the compression spring 105. Keep the front portion 101a closed to prevent fuel from flowing into the injection nozzle 5, and if the fuel pressure being pushed is greater than the elastic force of the compression spring 105, as shown in FIG. ) Is pushed backward by the fuel pressure to open the front portion 101a of the hollow portion of the housing 101 so that fuel can be introduced into the injection nozzle 5.

7 is a flowchart illustrating an operation procedure of the fuel injection device of the present invention as described above. Referring to FIG. 7 and other accompanying drawings, the operation of the fuel injection device of the present invention configured as described above is as follows. .

When a fuel having a predetermined pressure or more is pumped from the injection pump 1 through the injection pipe 7a to the flow limit 10, the fuel 102 flows into the injection nozzle while the ball 102 is retracted. When exceeded, the fuel is injected by lifting the needle 5a of the injection nozzle 5 as shown in FIG. 2, and then the injection is terminated while the needle 5a is closed when the fuel pressure to be pumped is below the closed transformer pressure. .

At this time, as shown in FIG. 3, the flow limit 10 is closed and at the same time, the pressure in the injection nozzle 5 pipe is increased by the reflected wave, and the after injection occurs in the highest injection pressure region. 5) When the pressure inside the tube is below the closed pressure, the needle (5a) is closed and the after injection is finished, and the injection nozzle (5) maintains a constant pressure and the end of one cycle.

On the other hand, when the operating pressure of the compression spring 105 of the flow limit 10 is set lower than the closed pressure, the flow limit is closed and the needle 5a of the injection nozzle 5 is lifted to cause post injection, and the compression spring 105 When the operating pressure is set higher than the closing pressure, the flow limit 10 is closed before the needle 5a of the injection nozzle 5 is closed, thereby effecting rapid spill.

As described above, according to the present invention, unlike the conventional positive pressure valve, as a flow limit, the fuel return to the pump or pipe is originally blocked to block the transmission of the reflected wave, and the after injection after the initial injection is generated by the energy. It is possible to make two injections in one cycle, and because the inside of the pipe is maintained at a high pressure, the injection delay period is shortened, thereby improving fuel efficiency and reducing nitrogen oxide (Nox) and fine material (PM) generation.

Claims (5)

An injection pump and an injection nozzle connected to the injection pump and the injection pipe via a medium to inject fuel supplied from the injection pump under a predetermined pressure into the combustion chamber, The fuel injection device for a diesel engine, characterized in that the flow restriction means for restricting the flow of fuel flowing to the injection nozzle is installed at the connection portion of the injection pipe and the injection nozzle. According to claim 1, wherein the flow restriction means is a hollow housing having one end coupled in communication with the end of the injection pipe and the other end is connected in communication with the inlet end of the injection nozzle, and is installed in the hollow portion of the housing and injected from the injection pipe A fuel injection device for a diesel engine, characterized in that it comprises an opening and closing means for opening the hollow portion at a set pressure or more during the forward flow of the fuel to the nozzle. 3. The opening and closing means of claim 2, wherein the opening and closing means includes a ball for closing the inlet end of the housing hollow portion, a retainer inserted and fixed to the outlet end side of the housing hollow portion, and elastically supporting the ball between the ball and the retainer. The fuel injection device for a diesel engine, characterized in that it comprises an elastic member, and a seat valve seated and supported by the ball and the end of the elastic member so that the elastic member can support the ball. 4. The fuel injection device for a diesel engine according to claim 3, wherein a shim for adjusting an elastic force of the elastic member is interposed between the elastic member and the retainer. The fuel injection device for a diesel engine according to claim 3 or 4, wherein the elastic member is a compression spring.